* {
  box-sizing: border-box;
}
a{
  text-decoration: none;
}
img{
  vertical-align: middle;
}
input,
button {
  /*点击高亮我们需要清除清除设置为transparent完成透明*/
  -webkit-tap-highlight-color: transparent;
  /*在移动端浏览器默认的外观在1OS上加上这个属性才能给按钮和输入框自定义样式*/
  /* -webkit-appearance: none; */
}

/*禁用长按页面时的弹出菜单*/
img,
a {
  -webkit-touch-callout: none;
}

body {
  width: 100%;
  min-width: 320px;
  max-width: 640px;
  margin: 0 auto;
  font-size: 14px;
  font-family: Courier, monospace;
  color: #666;
  line-height: 1.5;
}

header {
  background-color: #333;
  height: 45px;
  text-align: center;
  line-height: 45px;
  color: white;
  font-size: 18px;
  overflow: hidden;
}

header div:nth-child(1) {
  float: left;
  width: 10%;

}

header div:nth-child(1) img {
  width: 10px;
}

header div:nth-child(2) {
  float: left;
  width: 8%;
}

header div:nth-child(2) img {
  width: 30px;
  vertical-align: middle;
}

header div:nth-child(3) {
  float: left;
  width: 57%;
}

header div:nth-child(4) {
  float: left;
  width: 25%;
  height: 45px;
  background-color: #f63515;
}

.search_wrap {
  position: sticky;
  top: 0;
  max-width: 640px;
  min-width: 320px;
  width: 100%;
  height: 44px;
  color: white;
  background-color: #ff5454;
  overflow: hidden;
}

.search_wrap div:first-child {
  position: absolute;
  top: 0;
  left: 0;
  width: 40px;
}

.search_wrap div:first-child img {
  position: absolute;
  top: 13px;
  left: 13px;
  width: 20px;
}

.search_wrap div:nth-child(2) {
  position: relative;
  margin: 7px 45px;
  height: 30px;
  border-radius: 15px;
  background-color: #fff;
}

.search_wrap div:last-child {
  width: 40px;
  position: absolute;
  top: 0;
  right: 0;
  text-align: center;
  line-height: 44px;
}

.jd_logo {
  position: absolute;
  top: 8px;
  left: 8px;
  width: 20px;
  height: 30px;
  background: url("../images/jd-sprites.png") no-repeat;
  background-size: 200px 200px;
}

.jd_logo::after {
  content: "";
  position: absolute;
  right: -8px;
  top: 0px;
  border-right: 1px solid #ccc;
  display: block;
  width: 1px;
  height: 15px;
}

.search_logo {
  position: absolute;
  top: 8px;
  left: 40px;
  width: 20px;
  height: 30px;
  background: url("../images/jd-sprites.png") no-repeat -80px 0;
  background-size: 200px 200px;
}

.search {
  position: absolute;
  top: 5px;
  left: 60px;
  width: calc(100% - 70px);
  outline: none;
  border: 0;
}

.banner {
  width: 100%;
  height: 312px;
}

.banner img {
  width: 100%;
}

.jump {
  font-size: 0;
}

.jump img {
  width: 33.33%;
}

nav {
  width: 100%;
  overflow: hidden;
}
nav a {
  float: left;
  width: 20%;
  height: 81px;
  text-align: center;
}
nav a span{
  display: block;
  color: #666;;
}

nav a img{
  width: 40px;
  margin: 10px;
}
.choujiang {
  width: 100%;
  height: 207px;
}
.choujiang div{
  float: left;
}
.choujiang div:nth-child(1) {
  width: 50%;
} 
.choujiang div:nth-child(2) {
  width: 25%;
  border-left: 1px solid #ccc;
} 
.choujiang div:nth-child(3) {
  width: 25%;
  border-left: 1px solid #ccc;
} 
.choujiang img{
  width: 100%;
}